What Drives Willingness to Adopt Biofortified Crops? Evidence From Sweetpotato Farmers in Eswatini

Vitamin A deficiency remains a persistent public health challenge in Eswatini, disproportionately affecting rural populations reliant on staple crops with low micronutrient content. Biofortified crops such as orange-fleshed sweetpotato (OFSP) offer a sustainable, food-based solution; however, uptake has been uneven and often unsustained beyond the lifespan of development programmes. This study examines the determinants of smallholder farmers' willingness to adopt (WTA) biofortified sweetpotato in Eswatini, moving beyond conventional binary adoption frameworks. Using cross-sectional data from 202 farmers in the Manzini and Shiselweni regions, the study constructs a multidimensional WTA index capturing behavioural, socioeconomic, and institutional dimensions of adoption intention. An Ordered Probit Model (OPM) is then applied to identify key drivers. Trial participation in OFSP programmes, secondary education, prior sweetpotato yield, region, perceived risk, and self-perception significantly influence WTA. Notably, behavioural factors including risk perception and self-perception play a critical role alongside institutional and resource-access variables, while farmer group membership exerts a counterintuitive negative effect, suggesting limited functional capacity of groups in the study area. The study contributes to the biofortification literature by demonstrating that adoption operates as a continuum shaped by multiple interacting forces and underscores the importance of integrating behavioural insights into agricultural programme design. Policy recommendations focus on expanding hands-on OFSP exposure, addressing vine supply constraints, and revitalising farmer groups as effective knowledge-sharing platforms.